The invention is related to an ultrasonic transducer with a flange. Such ultrasonic transducers are used for all types of ultrasonic welding devices, for example wire bonders. Ultrasonic transducers of this type are generally known from U.S. Pat. Nos. 5,603,445, 5,595,328 and 5,364,005. To mount the ultrasonic transducer on the ultrasonic welding device, a flange is provided which is attached in a so-called longitudinal node of the longitudinal standing ultrasonic waves excited in the horn of the ultrasonic transducer. However, antinodes from radial oscillations occur in a node of the longitudinal ultrasonic waves, and therefore the flange is only connected to the horn by means of webs in order to prevent as much as possible the transmission of ultrasonic energy from the horn to the flange and on to the ultrasonic welding device. From the energetics point of view, the transmission of ultrasonic energy could be quite acceptable. Much graver disadvantages, however, can be seen in that the electrical impedance of the ultrasonic transducer is not reproducible and not constant and that the way in which the tip of the horn oscillates, even with energetic insignificant transmission of ultrasonic energy from the horn to the welding device, is still dependent on various circumstances, e.g., on how strongly the screws are tightened which secure the flange to the welding device. The oscillations of the tip of the horn are also dependent on how as capillary is secured to the horn as can be taken, for example, from U.S. Pat. Nos. 5,180,093 and 5,368,216.
The object of the invention is to propose an ultrasonic transducer with a flange for mounting on an ultrasonic welding device with which the above-mentioned disadvantages are overcome. A further object is to form the horn of the ultrasonic transducer in such a way that its tip carries out controllable oscillations even on the application of high frequency ultrasonic waves.